--- ray/src/rt/raytrace.c	1996/04/24 16:27:56	2.27
+++ ray/src/rt/raytrace.c	1998/08/06 10:30:38	2.32
@@ -1,7 +1,7 @@
-/* Copyright (c) 1996 Regents of the University of California */
+/* Copyright (c) 1998 Silicon Graphics, Inc. */
 
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static char SCCSid[] = "$SunId$ SGI";
 #endif
 
 /*
@@ -54,6 +54,8 @@ register RAY  *r, *ro;
 int  rt;
 double  rw;
 {
+	double	re;
+
 	if ((r->parent = ro) == NULL) {		/* primary ray */
 		r->rlvl = 0;
 		r->rweight = rw;
@@ -82,9 +84,15 @@ double  rw;
 		copycolor(r->albedo, ro->albedo);
 		r->gecc = ro->gecc;
 		r->slights = ro->slights;
-		r->rweight = ro->rweight * rw;
 		r->crtype = ro->crtype | (r->rtype = rt);
 		VCOPY(r->rorg, ro->rop);
+		r->rweight = ro->rweight * rw;
+						/* estimate absorption */
+		re = colval(ro->cext,RED) < colval(ro->cext,GRN) ?
+				colval(ro->cext,RED) : colval(ro->cext,GRN);
+		if (colval(ro->cext,BLU) < re) re = colval(ro->cext,BLU);
+		if (re > 0.)
+			r->rweight *= exp(-re*ro->rot);
 	}
 	rayclear(r);
 	return(r->rlvl <= maxdepth && r->rweight >= minweight ? 0 : -1);
@@ -96,12 +104,12 @@ register RAY  *r;
 {
 	r->rno = raynum++;
 	r->newcset = r->clipset;
+	r->robj = OVOID;
 	r->ro = NULL;
-	r->rot = FHUGE;
+	r->rt = r->rot = FHUGE;
 	r->pert[0] = r->pert[1] = r->pert[2] = 0.0;
 	setcolor(r->pcol, 1.0, 1.0, 1.0);
 	setcolor(r->rcol, 0.0, 0.0, 0.0);
-	r->rt = 0.0;
 }
 
 
@@ -269,9 +277,9 @@ double  coef;
 		backmat = rayshade(&br, back);
 					/* check for transparency */
 	if (backmat ^ foremat)
-		if (backmat)
+		if (!foremat && coef > FTINY)
 			raytrans(&fr);
-		else
+		else if (!backmat && coef < 1.0-FTINY)
 			raytrans(&br);
 					/* mix perturbations */
 	for (i = 0; i < 3; i++)
@@ -554,7 +562,8 @@ OBJECT  *cxs;
 	checkset(oset, cxs);			/* eliminate double-checking */
 	for (i = oset[0]; i > 0; i--) {
 		o = objptr(oset[i]);
-		(*ofun[o->otype].funp)(o, r);
+		if ((*ofun[o->otype].funp)(o, r))
+			r->robj = oset[i];
 	}
 	if (r->ro == NULL)
 		return(0);			/* no scores yet */